1. Field of the Invention
This invention relates to an insertable polymer positive temperature coefficient (PPTC) over-current protection device, and more particularly to an insertable PPTC over-current protection device including a PTC polymer matrix formed with at least one hole.
2. Description of the Related Art
U.S. Pat. No. 4,238,812 discloses an over-current protection device that includes a thin film PTC element, two electrodes formed on two opposite surfaces of the PTC element, and two conductive lead pins attached to the electrodes, respectively. The PTC element can be made from a polymer material containing a conductive filler.
There is a need to enhance the electrical properties, such as the high-voltage endurability, of the over-current protection device so as to protect the over-current protection device from being damaged by an overvoltage. Although the high-voltage endurability can be enhanced by increasing the area or the thickness of the PTC element, the size of the over-current protection device is undesirably increased.